Liquid venting surgical cassette

ABSTRACT

A surgical system having a cassette with an aspirant collection chamber and an aspiration vent line that draws fluid from the aspirant collection chamber. The pressure within the collection chamber is maintained near ambient so that when the aspiration vent line is open, fluid flows from the collection chamber and into the aspiration line. Such a system does not require a second source of irrigation fluid, minimizes pressure surges into the irrigation fluid line and does not affect the fluidic performance of the aspiration system. In addition, various vent pressures can be achieved by varying the vertical position of the reservoir relative to the aspiration line.

This application is a continuation-in-part of U.S. patent applicationSer. No. 09/771,945, filed Jan. 29, 2001, now U.S. Pat. No. 6,632,214 B4which is a divisional of U.S. patent application Ser. No. 09/387,357,filed Aug. 31, 1999, now U.S. Pat. No. 6,261,283 B1.

BACKGROUND OF THE INVENTION

This invention relates generally to the field of cataract surgery andmore particularly to an aspiration system for a handpiece for practicingthe phacoemulsification technique of cataract removal.

The human eye in its simplest terms functions to provide vision bytransmitting light through a clear outer portion called the cornea, andfocusing the image by way of the lens onto the retina. The quality ofthe focused image depends on many factors including the size and shapeof the eye, and the transparency of the cornea and lens.

When age or disease causes the lens to become less transparent, visiondeteriorates because of the diminished light which can be transmitted tothe retina. This deficiency in the lens of the eye is medically known asa cataract. An accepted treatment for this condition is surgical removalof the lens and replacement of the lens function by an artificialintraocular lens (IOL).

In the United States, the majority of cataractous lenses are removed bya surgical technique called phacoemulsification. During this procedure,a thin phacoemulsification cutting tip is inserted into the diseasedlens and vibrated ultrasonically. The vibrating cutting tip liquifies oremulsifies the lens so that the lens may be aspirated out of the eye.The diseased lens, once removed, is replaced by an artificial lens.

A typical ultrasonic surgical device suitable for ophthalmic proceduresconsists of an ultrasonically driven handpiece, an attached cutting tip,and irrigating sleeve and an electronic control console. The handpieceassembly is attached to the control console by an electric cable andflexible tubings. Through the electric cable, the console varies thepower level transmitted by the handpiece to the attached cutting tip andthe flexible tubings supply irrigation fluid to and draw aspirationfluid from the eye through the handpiece assembly.

The operative part of the handpiece is a centrally located, hollowresonating bar or horn directly attached to a set of piezoelectriccrystals. The crystals supply the required ultrasonic vibration neededto drive both the horn and the attached cutting tip duringphacoemulsification and are controlled by the console. The crystal/hornassembly is suspended within the hollow body or shell of the handpieceby flexible mountings. The handpiece body terminates in a reduceddiameter portion or nosecone at the body's distal end. The nosecone isexternally threaded to accept the irrigation sleeve. Likewise, the hornbore is internally threaded at its distal end to receive the externalthreads of the cutting tip. The irrigation sleeve also has an internallythreaded bore that is screwed onto the external threads of the nosecone.The cutting tip is adjusted so that the tip projects only apredetermined amount past the open end of the irrigating sleeve.Ultrasonic handpieces and cutting tips are more fully described in U.S.Pat. Nos. 3,589,363; 4,223,676; 4,246,902; 4,493,694; 4,515,583;4,589,415; 4,609,368; 4,869,715; 4,922,902; 4,989,583; 5,154,694 and5,359,996, the entire contents of which are incorporated herein byreference.

In use, the ends of the cutting tip and irrigating sleeve are insertedinto a small incision of predetermined width in the cornea, sclera, orother location. The cutting tip is ultrasonically vibrated along itslongitudinal axis within the irrigating sleeve by the crystal-drivenultrasonic horn, thereby emulsifying the selected tissue in situ. Thehollow bore of the cutting tip communicates with the bore in the hornthat in turn communicates with the aspiration line from the handpiece tothe console. A reduced pressure or vacuum source in the console draws oraspirates the emulsified tissue from the eye through the open end of thecutting tip, the cutting tip and horn bores and the aspiration line andinto a collection device. The aspiration of emulsified tissue is aidedby a saline flushing solution or irrigant that is injected into thesurgical site through the small annular gap between the inside surfaceof the irrigating sleeve and the cutting tip.

During surgery, the hollow, resonating tip can become occluded. Duringocclusion, vacuum can build in the aspiration line downstream of theocclusion. When the occlusion eventually breaks apart, this pent upvacuum is released into the eye which can, depending upon the amount ofvacuum, draw a significant amount of fluid from the eye, therebyincreasing the risk of anterior chamber collapse. To address thisconcern, modern surgical console can detect increases in aspiration linevacuum beyond normal operating parameters and therefore predictocclusions. These consoles can then either stop or slow the aspirationpump, or sound an alarm so that the surgeon can take appropriateprecautions.

The cassettes used in modern consoles also allow the aspiration line tobe vented, either to atmosphere or to a liquid so as to reduce oreliminate vacuum surge upon occlusion break. Prior art air ventedcassettes allow ambient air to enter the aspiration line, however,venting air into the aspiration line changes the fluidic performance ofthe aspiration system. Liquid venting systems allow irrigation fluid tobleed into the aspiration line, thereby reducing any impact on thefluidic performance of the aspiration system. Liquid venting cassettesare more fully described in U.S. Pat. Nos. 4,832,685 and 4,935,005(Haines) and U.S. Pat. No. 4,713,051 (Steppe, et al.), the entirecontents of which being incorporated herein by reference. When higheraspiration vacuums are used, cassettes that vent the aspiration line tothe irrigation line can cause high pressure surges in the irrigationline. Other systems provide a separate source of irrigation fluid tovent the aspiration line, requiring the use of two irrigation fluidsources and increasing the cost and complexity of the system.

Therefore, a need continues to exist for a simple surgical system thatallows rapid venting of excess aspiration vacuum without introducingpressure variations in the irrigation line or the downstream aspirationline.

BRIEF SUMMARY OF THE INVENTION

The present invention improves upon the prior art by providing asurgical system having a cassette with an aspirant collection chamberand an aspiration vent line that draws fluid from the aspirantcollection chamber. The pressure within the collection chamber ismaintained near ambient so that when the aspiration vent line is open,fluid flows from the collection chamber and into the aspiration line.Such a system does not require a second source of irrigation fluid,minimizes pressure surges into the irrigation fluid line and does notaffect the fluidic performance of the aspiration system. In addition,various vent pressures can be achieved by varying the vertical positionof the reservoir relative to the aspiration line.

Accordingly, one objective of the present invention is to provide asurgical system having a aspiration line vent.

Another objective of the present invention is to provide a surgicalsystem having a cassette that allows the aspiration line to be vented ofexcess vacuum.

Another objective of the present invention is to provide a surgicalsystem having a cassette that vents the aspiration line to an aspirantcollection chamber.

Another objective of the present invention is to provide a surgicalsystem that vents the aspiration line without introducing pressuresurges in the irrigation line.

Another objective of the present invention is to provide a surgicalsystem that vents the aspiration line without affecting the fluidicperformance of the aspiration system.

These and other advantages and objectives of the present invention willbecome apparent from the detailed description and claims that follow.

BRIEF DESCRIPTION OF THE DRAWING

The drawing is a schematic illustration of the system and cassette ofthe present invention.

DETAILED DESCRIPTION OF THE INVENTION

System 10 of the present invention generally includes surgical console12 and cassette 14. Console 12 may be any suitably modified commerciallyavailable surgical console, such as the SERIES TWENTY THOUSAND® LEGACY®or ACCURUS® surgical systems available from Alcon Laboratories, FortWorth, Tex. Cassette 14 may be any suitably modified commerciallyavailable surgical cassettes, such as those described in U.S. Pat. Nos.5,267,956, 5,364,342 and 5,499,969 (Beuchat, et al.) and U.S. Pat. No.5,899,674 (Jung, et al.), the entire contents of which beingincorporated herein by reference. Cassette 14 is held in operativeassociation with console 12 by means well-known in art.

As seen in the figure, console 12 generally contains aspiration pumpmechanism 16, which may be any suitable flow or vacuum based pump, suchpumps being widely known in the art. For example, pump mechanism 16 maybe a peristaltic pump roller head that interacts with a peristaltic pumptube formed by aspiration line 20 and aspiration exhaust line 34.Aspiration line 20 is connected to surgical handpiece 22 on one end andend 18 of aspiration line 20 opposite handpiece 22 interacts with pumpmechanism 16 so as to draw fluid through handpiece 22. Aspiration line20 is intersected between handpiece 22 and 18 by aspiration vent line24. In fluid communication with aspiration vent line 24 is pressuresensor 26, which may be one of a variety of invasive or noninvasivepressure sensors well-known in the art.

Cassette 14 generally contains fluid reservoir 28. Extending fromreservoir 28 at or near bottom 29 is aspiration vent line 32, whichfluidly connects to aspiration vent line 24 through vent valve 30.Aspirant or exhaust from pump mechanism 16 is directed into reservoir 28through aspiration exhaust line 34. Reservoir 28 may also vent toambient through fluid line 41, waste bag 40 and vent line 36, which maycontain antimicrobial filter 38.

As discussed above, while it is preferred that pump mechanism 16 be aperistaltic roller head and aspiration line 20 and aspiration exhaustline 34 be formed in one continuous length so as to form a peristalticpump tube that interacts with pump mechanism 16, one skilled in the artwill recognize that aspiration line 20 and aspiration exhaust line maybe formed as a separate piece or pieces or may be formed integrally withcassette 14 and that pump mechanisms 16 other that peristaltic pumproller heads may be used, such as linear peristaltic pumps.

In addition, pressure sensor 26 is depicted as being contained withinconsole 12. One skilled in the art will recognize that portions ofpressure sensor 26, such as a pressure diaphragm (not shown) may becontained in or on cassette 14 and interact with a force transducer orother means (not shown) contained within console 12.

In use, cassette 14 is installed on or within console 12 and held inoperative association with console 12 by means well-known in the art.System 10 is primed initially with clean surgical fluid so that a smallamount of fluid fills reservoir 28. During surgery, pump mechanism 16draws aspirant through handpiece 22 and into reservoir 28. If the vacuumwithin aspiration line 20 is too high and needs to be vented, vent valve30 is opened allowing aspirant to be drawn off of bottom 29 of reservoir28 (reservoir 28 being at or near ambient) and into aspiration line 20(which contains a vacuum) through aspiration vent line 24. One skilledin the art will recognize that by varying the vertical position ofreservoir 28 relative to aspiration line 20, various vent head pressuresmay be achieved. Reservoir 28 may be relatively small, and not capableof holding all of the aspirant collected during surgery. Waste bag 40may be used to drain and hold excess fluid from reservoir 28, throughfluid line 41 above bottom 29 of reservoir 28. Waste bag 40 may beintegrally formed within cassette 14 or may be formed as a separatecollapsible bag attached to cassette 14, as is well-known in the art.

This description is given for purposes of illustration and explanation.It will be apparent to those skilled in the relevant art that changesand modifications may be made to the invention described above withoutdeparting from its scope or spirit.

We claim:
 1. A cassette capable of operative association with a surgicalconsole, comprising: a) a body, the body having a fluid reservoir, b) anaspiration vent line extending through the body from the reservoir at ornear a bottom of the reservoir, the aspiration vent line fluidlyconnecting the reservoir to an aspiration line; c) a waste bag fluidlyconnected to the reservoir above the bottom of the reservoir; and d) avent valve located in the body in the aspiration vent line.